[PATCH] for_each_pgdat macro

Patch from Robert Love.

This patch implements for_each_pgdat(pg_data_t *) which is a helper
macro to cleanup code that does a loop of the form:

        pgdat = pgdat_list;
        while(pgdat) {
	        /* ... */
	        pgdat = pgdat->node_next;
	}

and replace it with:

	for_each_pgdat(pgdat) {
		/* ... */
	}

This code is from Rik's 2.4-rmap patch and is by William Irwin.

arch/ia64/mm/init.c

@@ -167,10 +167,10 @@ show_mem(void)
 
 #ifdef CONFIG_DISCONTIGMEM
 	{
-		pg_data_t *pgdat = pgdat_list;
+		pg_data_t *pgdat;
 
 		printk("Free swap:       %6dkB\n", nr_swap_pages<<(PAGE_SHIFT-10));
-		do {
+		for_each_pgdat(pgdat) {
 			printk("Node ID: %d\n", pgdat->node_id);
 			for(i = 0; i < pgdat->node_size; i++) {
 				if (PageReserved(pgdat->node_mem_map+i))
@@ -184,8 +184,7 @@ show_mem(void)
 			printk("\t%d reserved pages\n", reserved);
 			printk("\t%d pages shared\n", shared);
 			printk("\t%d pages swap cached\n", cached);
-			pgdat = pgdat->node_next;
-		} while (pgdat);
+		}
 		printk("Total of %ld pages in page table cache\n", pgtable_cache_size);
 		printk("%d free buffer pages\n", nr_free_buffer_pages());
 	}

include/linux/mmzone.h

@@ -136,7 +136,7 @@ typedef struct pglist_data {
 	unsigned long node_start_mapnr;
 	unsigned long node_size;
 	int node_id;
-	struct pglist_data *node_next;
+	struct pglist_data *pgdat_next;
 } pg_data_t;
 
 extern int numnodes;
@@ -163,6 +163,20 @@ extern void free_area_init_core(int nid, pg_data_t *pgdat, struct page **gmap,
 
 extern pg_data_t contig_page_data;
 
+/**
+ * for_each_pgdat - helper macro to iterate over all nodes
+ * @pgdat - pointer to a pg_data_t variable
+ *
+ * Meant to help with common loops of the form
+ * pgdat = pgdat_list;
+ * while(pgdat) {
+ * 	...
+ * 	pgdat = pgdat->pgdat_next;
+ * }
+ */
+#define for_each_pgdat(pgdat) \
+	for (pgdat = pgdat_list; pgdat; pgdat = pgdat->pgdat_next)
+
 #ifndef CONFIG_DISCONTIGMEM
 
 #define NODE_DATA(nid)		(&contig_page_data)

mm/bootmem.c

@@ -49,7 +49,7 @@ static unsigned long __init init_bootmem_core (pg_data_t *pgdat,
 	bootmem_data_t *bdata = pgdat->bdata;
 	unsigned long mapsize = ((end - start)+7)/8;
 
-	pgdat->node_next = pgdat_list;
+	pgdat->pgdat_next = pgdat_list;
 	pgdat_list = pgdat;
 
 	mapsize = (mapsize + (sizeof(long) - 1UL)) & ~(sizeof(long) - 1UL);
@@ -339,12 +339,11 @@ void * __init __alloc_bootmem (unsigned long size, unsigned long align, unsigned
 	pg_data_t *pgdat = pgdat_list;
 	void *ptr;
 
-	while (pgdat) {
+	for_each_pgdat(pgdat)
 		if ((ptr = __alloc_bootmem_core(pgdat->bdata, size,
 						align, goal)))
 			return(ptr);
-		pgdat = pgdat->node_next;
-	}
+
 	/*
 	 * Whoops, we cannot satisfy the allocation request.
 	 */

mm/numa.c

@@ -98,19 +98,19 @@ struct page * _alloc_pages(unsigned int gfp_mask, unsigned int order)
 	if (!next)
 		next = pgdat_list;
 	temp = next;
-	next = next->node_next;
+	next = next->pgdat_next;
 #endif
 	start = temp;
 	while (temp) {
 		if ((ret = alloc_pages_pgdat(temp, gfp_mask, order)))
 			return(ret);
-		temp = temp->node_next;
+		temp = temp->pgdat_next;
 	}
 	temp = pgdat_list;
 	while (temp != start) {
 		if ((ret = alloc_pages_pgdat(temp, gfp_mask, order)))
 			return(ret);
-		temp = temp->node_next;
+		temp = temp->pgdat_next;
 	}
 	return(0);
 }

mm/page_alloc.c

@@ -480,7 +480,7 @@ unsigned int nr_free_pages(void)
 	unsigned int i, sum = 0;
 	pg_data_t *pgdat;
 
-	for (pgdat = pgdat_list; pgdat; pgdat = pgdat->node_next)
+	for (pgdat = pgdat_list; pgdat; pgdat = pgdat->pgdat_next)
 		for (i = 0; i < MAX_NR_ZONES; ++i)
 			sum += pgdat->node_zones[i].free_pages;
 
@@ -489,10 +489,10 @@ unsigned int nr_free_pages(void)
 
 static unsigned int nr_free_zone_pages(int offset)
 {
-	pg_data_t *pgdat = pgdat_list;
+	pg_data_t *pgdat;
 	unsigned int sum = 0;
 
-	do {
+	for_each_pgdat(pgdat) {
 		zonelist_t *zonelist = pgdat->node_zonelists + offset;
 		zone_t **zonep = zonelist->zones;
 		zone_t *zone;
@@ -503,9 +503,7 @@ static unsigned int nr_free_zone_pages(int offset)
 			if (size > high)
 				sum += size - high;
 		}
-
-		pgdat = pgdat->node_next;
-	} while (pgdat);
+	}
 
 	return sum;
 }
@@ -529,13 +527,12 @@ unsigned int nr_free_pagecache_pages(void)
 #if CONFIG_HIGHMEM
 unsigned int nr_free_highpages (void)
 {
-	pg_data_t *pgdat = pgdat_list;
+	pg_data_t *pgdat;
 	unsigned int pages = 0;
 
-	while (pgdat) {
+	for_each_pgdat(pgdat)
 		pages += pgdat->node_zones[ZONE_HIGHMEM].free_pages;
-		pgdat = pgdat->node_next;
-	}
+
 	return pages;
 }
 #endif
@@ -613,7 +610,7 @@ void show_free_areas(void)
 		K(nr_free_pages()),
 		K(nr_free_highpages()));
 
-	for (pgdat = pgdat_list; pgdat; pgdat = pgdat->node_next)
+	for (pgdat = pgdat_list; pgdat; pgdat = pgdat->pgdat_next)
 		for (type = 0; type < MAX_NR_ZONES; ++type) {
 			zone_t *zone = &pgdat->node_zones[type];
 			printk("Zone:%s "
@@ -635,7 +632,7 @@ void show_free_areas(void)
 		ps.nr_writeback,
 		nr_free_pages());
 
-	for (pgdat = pgdat_list; pgdat; pgdat = pgdat->node_next)
+	for (pgdat = pgdat_list; pgdat; pgdat = pgdat->pgdat_next)
 		for (type = 0; type < MAX_NR_ZONES; type++) {
 			list_t *elem;
 			zone_t *zone = &pgdat->node_zones[type];

mm/vmscan.c

@@ -471,7 +471,7 @@ static void kswapd_balance(void)
 		pgdat = pgdat_list;
 		do
 			need_more_balance |= kswapd_balance_pgdat(pgdat);
-		while ((pgdat = pgdat->node_next));
+		while ((pgdat = pgdat->pgdat_next));
 	} while (need_more_balance);
 }
 
@@ -499,7 +499,7 @@ static int kswapd_can_sleep(void)
 		if (kswapd_can_sleep_pgdat(pgdat))
 			continue;
 		return 0;
-	} while ((pgdat = pgdat->node_next));
+	} while ((pgdat = pgdat->pgdat_next));
 
 	return 1;
 }